1. Field of the Invention
The present invention concerns methods and apparatuses for high-speed control and/or switching of lamp intensities and/or wavelengths and for high-speed optical data communication.
2. Discussion of the Background
Light sources or lamps containing materials which, in the vapor state, are responsible directly or indirectly for illumination but which are at least partially solid or liquid under typical conditions of storage and/or use of the lamp (e.g., a temperature of from 15.degree. C. to 350.degree. C. or more, a pressure from a near vacuum [e.g., 0.01 atm] to several atm or more) are well-known, and are used frequently in particular fields of technology. Such lamps include vapor arc lamps (e.g., mercury arc lamps), plasma arc lamps and halogen lamps (e.g., containing a tungsten filament and iodine crystals), and may include other light sources such as sodium lamps.
For example, vapor arc lamps are typically used in photochemistry (see Kirk-Othmer Encyclopedia of Chemical Technology, 3rd ed. (1982), vol. 17, pages 545-553). Mercury vapor arc lamps of the high-pressure type produce an output of 1-10,000 W of power, and are useful for ultraviolet curing, photochemical reactions, etc. Mercury vapor arc lamps of the low-pressure type produce an output of 1-400 W of power, and are useful for photosterilization, photochemical reactions, etc. Mercury vapor arc lamps of the capillary type produce an output of 1.5-5 kW of power, and are useful for ultraviolet polymerization, projection, photochemical reactions and biological research.
The so-called "halogen" lamps contain as an active illumination material a metal or alloy filament (e.g., of Group VIb metals [Cr, Mo, W]), and as an auxiliary material, a halogen (e.g., Cl.sub.2, Br.sub.2, I.sub.2). Halogen lamps provide significant advantages in longevity and in light output over non-halogen-containing filament bulbs. In a halogen lamp, metal atoms which escape from the filament as vapor react with the halogen molecules, thus preventing metal deposits from forming on the inner surface of the bulb. As the formed metal halide returns near the filament, the heat from the active filament provides the energy for separating metal from halide, thus recycling the metal back to the filament.
Metal halide lamps also exist as so-called "short arc" lamps. Short arc metal halide lamps have high luminance and high efficacy, thus providing particular advantages as projection light sources (e.g., in slide projectors and in overhead projectors). Halogen lamps are also useful in photocopiers and as high-power illumination sources (e.g., stadium lamps, spotlights).
Such lamps rely on materials which must be in the vapor state to achieve the desired results and/or advantages. However, many such materials are also at some point at least partly in the solid or liquid state prior to or during use. Prior to the present invention, however, one merely had to wait until the lamp heated up to a temperature which resulted in complete vaporization of the partially solid or liquid materials in order to take full advantage of the technology. As a result, many high-speed applications using such lamps have been unattainable.
Fiber optic communication apparatuses and methods are well-known, and are useful for transmitting data over both long distances (e.g., telecommunications, cable television service, communications equipment for remote-site journalism and for military applications, etc.) and short distances (e.g., local-area computer networks and signal transmission in environments subject to severe electromagnetic interference; for reviews on fiber optics and fiber optic communications, see Kirk-Othmer Encyclopedia of Chemical Technology, 4th ed. (1993), vol. 10, pages 514-538 and references cited therein, and J. Hecht, "Understanding Fiber Optics," Howard W. Sams and Co., Indianapolis, Indiana (1987)). However, light sources for generating the transmitted light signals are typically limited to lasers or light-emitting diodes (LEDs), which are limited in (i) the power with which the signals can be sent and (ii) the wavelengths of light which can be generated.